JPH11254729A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an imaging device in which excellent image quality and high reliability are ensured by flying a toner surely through the aperture of an aperture electrode and preventing a toner passing between apertures and uncontributive to printing from entering into the aperture. SOLUTION: An aperture electrode is provided, on the upstream side in the carrying direction of toner, with a protrusion 7 divided to match the openings. A toner being carried on a toner carrying roller to enter into the aperture 6 touches the protrusion 7 and subjected to mechanical action such that the restraining force of the toner carrying roller is weakened and the toner is guided in the direction of the aperture. Since the mechanical action has no effect on the toner which must not entering into the aperture 6, image quality is prevented from deteriorating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus applicable to a copying machine, a printer, a plotter, a facsimile machine and the like, and more particularly to an apparatus for forming an image by controlling the passage of a charged body through an opening. .

[0002]

2. Description of the Related Art Conventionally, in this type of image forming apparatus,
By applying an image signal to a control electrode formed corresponding to an opening (aperture), an image signal is recorded on a support which is a recording medium by controlling the passage of charged particles such as toner through the aperture. Known (eg, US Pat.
689935).

The image forming apparatus described in this US Patent has a continuous shield electrode on one side of an insulator layer and a plurality of control electrodes insulated from each other on the other side. An aperture electrode body formed through three layers for each of the plurality of insulated control electrodes and having at least one row of apertures, and a control electrode and a shield electrode are selectively provided. Means for applying a potential, means for supplying charged toner particles to the aperture of the aperture electrode body, and a back electrode to which a high voltage is applied, which is disposed on the side of the transported support opposite to the aperture electrode body; Means for transporting the body relative to the aperture electrode body to position the support in the toner particle flow path.

However, in this image forming apparatus,
The toner particles are easily clogged in the aperture, which may lower the recording quality. In order to solve this problem, the present applicant has proposed an image recording apparatus in which a carrier holding toner and an aperture electrode are arranged in contact with each other (see Japanese Patent Application Laid-Open No. H6-155798). ).
According to this configuration, the aperture is not clogged, and an improvement in image quality is expected.

[0005]

Further, in the above image forming apparatus, the necessary contact pressure between the toner carrier and the aperture electrode is limited to only the vicinity of the aperture.
The present applicant has been studying that the toner does not adhere to the aperture electrode body and the printing quality and durability are further improved. As one of the constitutions, it has been considered that a convex portion is provided at an upstream portion of the aperture and a contact pressure is applied to the inflowing toner. However, with this configuration, the contact pressure must be applied to the toner that does not contribute to printing without passing through the aperture, that is, it should pass between the apertures. This can cause problems.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. The present invention is directed to applying a contact pressure to a toner to enter an aperture of an aperture electrode body to release a binding force of the toner and to apply a force to the aperture. By making it easier to enter, and by preventing contact pressure from being applied to toner that should pass between apertures and does not contribute to recording, accurate toner flight is possible, and therefore, excellent image quality and reliability are obtained. It is an object to provide an image forming apparatus.

[0007]

SUMMARY OF THE INVENTION To achieve this object, a first aspect of the present invention is a charged body control means having an opening and a control electrode provided corresponding to the opening, and the charged body control means. A charged body carrier that carries and transports a charged body, and the charged body carrier includes a back electrode provided on the opposite side across the charged body control means, and by controlling energization to the control electrode, In an image forming apparatus that controls the passage of a charged body conveyed by a charged body carrier through an opening and forms an image on a support body supported on a back electrode, a charged body control unit includes a charged body carrier. The conveying means is provided with means for mechanically acting on the charged body to be entered into the opening to change the restraining force received by the charged body from the charged body carrier and guiding the charged body in the opening direction. is there. In this configuration, of the charged bodies to be transported, only the charged body that should enter the opening mechanically acts, and the adhesion of the charged body to the carrier changes from static friction to dynamic friction, whereby the charged body is The binding force received from the carrier is weakened, and the charged body is guided in the opening direction, so that the charged body easily flies. The charged body that should not enter the opening has no mechanical action, so that the image quality does not deteriorate.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the charged body control means is divided corresponding to the opening on the upstream side in the transport direction of the charged body by the charged body carrier. It is provided with a convex portion. In this configuration, the charged body to enter the opening by the divided convex portions receives a mechanical action, and the above-described action is obtained.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the convex portion is gently raised in a direction in which the charged body is transported by the charged body carrier. . In this configuration, as the charged body is transported, the adhesive force of the charged body to the carrier is weakened, and the above-described action can be obtained smoothly.

According to a fourth aspect of the present invention, in the image forming apparatus according to the second or third aspect, the control electrode of the charged body control means is provided on the insulating sheet member. The surface opposite to the surface on which the control electrode is provided is in contact with the charge carrier, and the convex portion is provided on the side in contact with the charge carrier. In this configuration, the convex portion directly mechanically acts on the charged body carried on the charged body carrier, so that the above-described action can be reliably obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a main configuration of an image forming apparatus according to the present invention. Image forming apparatus 10
Reference numeral 0 denotes an aperture electrode body 1 (charged body control means) as toner flow control means, and a columnar back electrode roller as a back electrode having a gap of 1 mm above the aperture electrode body 1. 22 (back electrode) is rotatably disposed on a housing (not shown). This back electrode roller 22
Is disposed to face a toner carrying roller 14 described later via an aperture 6 of the aperture electrode body 1. In a gap between the aperture electrode body 1 and the back electrode roller 22, a support P (recording medium) such as a sheet on which an image is recorded is carried in by a transport roller (not shown). In the aperture electrode body 1, a control electrode 4 is formed on an insulating sheet member 2 so as to correspond to an opening (aperture) 6.

A toner supply device 1 is provided below the aperture electrode body 1 along the longitudinal direction of the aperture electrode body 1.
0 is provided. A fixing device 26 is provided at a position where the support P conveyed by the back electrode roller 22 advances. The toner supply device 10 includes a toner case 11 also serving as a housing of the entire device, a toner 16 (charged body) stored in the toner case 11, and a supply roller 12.
And a toner carrying roller 14 (charged body carrying body) as a toner carrying body, and a toner layer regulating blade 18. The toner carrying roller 14 carries the toner 16 in a layer shape and transports the toner 16 toward the aperture electrode body 1. The supply roller 12 supplies the toner 16 to the toner carrying roller 14. The supply roller 12 and the toner carrying roller 14 are supported in the toner case 11 so as to be rotatable in the direction of the arrow shown in the drawing, and are arranged in contact with each other. Further, the toner layer regulating blade 1
Numeral 8 is for adjusting the amount of toner 16 carried on the toner carrying roller 14 to be uniform on the roller surface and for uniformly charging the toner 16. I have.

The control voltage application circuit 8 includes the aperture electrode 1
Is connected to the control electrode 4. The control voltage application circuit 8 is configured to selectively apply +40 V (ON voltage) or −20 V (OFF voltage) to the control electrode 4 based on image data input from a data input unit (not shown). Have been.

The back electrode roller 22 is disposed with a gap of about 1 mm from the aperture electrode body 1 and is rotatably supported by a chassis (not shown), so that the back electrode roller 22 and the aperture electrode body 1 The support P can be inserted into the gap. A DC power supply 24 is connected to the back electrode roller 22, and the DC power supply 24 is configured to be able to apply a voltage of +1 kV to the back electrode roller 22.

The transport device for transporting the support P is composed of a pair of transport rollers (not shown) and a fixing device 26. The support P inserted from an insertion port (not shown)
The sheet is nipped by a pair of conveying rollers, and is conveyed to the fixing device 26 through a position where the back electrode roller 22 is an image forming position. The fixing device 26 includes a heat roller having a heat source therein and a pressure roller pressed against the heat roller. The support P on which the image is formed is sandwiched between the two rollers in the fixing device 26, and after the toner image is heat-fixed, is discharged out of the image forming apparatus through a discharge port (not shown).

Next, the structure of the aperture electrode body 1 will be described.
This will be described with reference to FIGS. The aperture electrode body 1
A plurality of rectangular apertures 6 (openings) penetrating the insulating sheet 2 are arranged in a row at equal intervals on a polyimide insulating sheet 2 having a thickness of 25 μm. On the periphery of two sides of the aperture 6, the control electrode 4 as a toner flow control unit is formed with a thickness of 8 μm. Furthermore, a plurality of drive I
C5 is arranged. The control electrode 4 is connected to the conducting wire 3,
The drive IC 5 is connected to the conductor 3. As shown in FIG. 1, the aperture electrode body 1 is disposed so as to be in contact with the toner on the toner carrying roller 14 at the position of the aperture 6 of the insulating sheet 2 in a state where the control electrode 4 faces the support P. I have.

Further, as shown in FIG. 3, the insulating sheet 2 of the aperture electrode body 1 has a back surface (a surface that can be in contact with the toner carrying roller 14) opposite to the surface on which the control electrodes 4 are provided. A convex portion 7 is provided upstream of the aperture 6 (the direction of toner conveyance is indicated by an arrow). Convex part 7
Are arranged only on the upstream side of each aperture 6 in the toner transport direction, and are not provided in a portion corresponding to a lower portion of the control electrode 4. The convex portion 7 is raised toward the downstream side in the toner conveying direction, has a height of several microns, and has a width of the aperture 6.
, And has a length of several microns to several tens of microns in the upstream and downstream directions.

Next, the operation of the image forming apparatus 100 configured as described above will be described. From an external device (not shown)
When an image forming command is input to the image forming apparatus 100, first, the toner carrying roller 14 and the supply roller 12
Start rotation in the direction of the arrow shown in FIG. Then, the toner 16 carried and carried on the surface of the supply roller 12 is
Rubbed against the surface of the toner carrying roller 14;
By being negatively charged, the toner carrying roller 14
Carried on the surface of The carried toner 16 is uniformly thinned by the toner layer regulating blade 18, is charged substantially uniformly, and is then conveyed toward the aperture electrode body 1 by the rotation of the toner carrying roller 14. Then, the toner 16 on the toner carrying roller 14 is supplied under the aperture 6 while being rubbed by the insulating sheet 2 of the aperture electrode body 1.

On the other hand, the support P is transported between the aperture electrode body 1 and the back electrode roller 22 while being sandwiched by transport rollers. A voltage is applied to the control electrode 4 based on the print data. The ON voltage (+
40V), and OFF voltage (−20)
V) is applied from a control voltage application circuit 8 (not shown). When an ON voltage (+40 V) is applied to the control electrode 4, an electric force line from the control electrode 4 to the toner carrying roller 14 is formed due to a potential difference between the control electrode 4 and the toner carrying roller 14. As a result, the negatively charged toner 16 receives an electrostatic force in the direction of higher potential, passes through the aperture 6 from above the toner carrying roller 14, and is drawn out to the control electrode 4 side. The extracted toner 16 further flies toward the support P by an electric field formed between the support P and the aperture electrode body 1 by the voltage of +1 kV applied to the back electrode roller 22. As a result, the toner 16 flying toward the support P accumulates on the support P to form pixels.

Further, the OFF voltage (−20) is applied to the control electrode 4.
When V) is applied, electric lines of force from the toner carrying roller 14 to the control electrode 4 are formed. as a result,
The negatively charged toner receives an electrostatic force in a direction pressed against the carrying roller 14, and therefore does not pass through the aperture 6. The support P is transported by one pixel in the direction perpendicular to the aperture row by the support transport unit while one row of pixels is formed by the toner 16 on the surface. By repeating such a process, a toner image representing a desired image is formed on the entire surface of the support P. Thereafter, the formed toner image is fixed on the support P by the fixing device 26. Thereafter, the support P on which the toner image is formed is
The sheet is discharged out of the image forming apparatus from a discharge port (not shown).

Through the above process, the toner 16
Is performed, the following effects can be obtained by applying the present invention. That is, the toner 16 placed on the carrying roller 14 reaches the aperture electrode 1. Since the convex portion 7 is provided only before the aperture 6, only the toner 16 entering the aperture 6 comes into contact with the convex portion 7.
By this contact, the toner 16 is released from mechanical restraining force such as van der Waals force (toner carrying roller 14).
The adhesive force to the surface changes from static friction to dynamic friction), and the state is controlled by the electric field driving force.

As described above, the toner 16 entering the aperture 6
Since the mechanical force is only applied to the toner 16, the toner 16 directly contributing to printing can be made to fly with the restraining force loosened. On the other hand, toner that does not enter the aperture 6, that is, toner that does not contribute to printing, can pass near the aperture 6 while being restrained. Since such toner is not excited by mechanical force, it flows extremely stably,
No uncontrolled toner such as fogging is generated. Thus, efficient electric field control becomes possible, and as a result, a high-quality and highly reliable printing state is obtained.

FIG. 4 shows a configuration near the aperture according to the second embodiment. In this embodiment, as described above, the convex portion 7 is provided not only on the upstream side of the aperture 6 but on the upstream side of the aperture 6 in the direction in which the apertures 6 are arranged. 7 are provided.
The toner that does not normally flow into the aperture 6 due to the convex portion 7 is also guided by the aperture 6 and can contribute to printing.

FIG. 5 shows a configuration near the aperture according to the third embodiment. In this embodiment, the convex portion 7 is formed in a trapezoidal shape (the side in the downstream direction is short) at the upstream position corresponding to the aperture 6, and is protruded toward the downstream side.
Also in this configuration, an operation equivalent to that of the second embodiment can be obtained.

The present invention is not limited to the configuration of the embodiment described in detail above, and various changes can be made without departing from the gist of the present invention. In the present embodiment, the so-called toner, which is a dry powder, has been described. However, any material can be equally applied as long as it is a charged printing material. For example, liquid toner,
Good effects can also be obtained with liquid developing materials such as charged ink. Further, in the present embodiment, a so-called single-color unit has been described, but the present invention can be similarly applied to a color image forming apparatus in which a plurality of units are arranged.

[0026]

As described above, according to the image forming apparatus of the first aspect of the present invention, by applying a mechanical force only to the charged body that enters the opening, the charged body that does not enter the opening can be reduced.
Since the restraining force is not weakened, an uncontrolled state such as fogging is prevented, and good image recording becomes possible.

According to the image forming apparatus of the second aspect of the invention, in addition to the effects of the first aspect, the convex portion divided on the upstream side in the carrying direction of the carrier corresponding to the opening is provided. In addition, a mechanical action can be appropriately given, and more stable image recording can be performed.

In the image forming apparatus according to the third aspect of the present invention, the convex portion is raised in the transport direction, so that a smooth mechanical action can be provided, and the above-described effects can be reliably obtained. Can be

Further, according to the image forming apparatus of the fourth aspect of the present invention, since the convex portion is in direct contact with the charged body, the above-mentioned effects are remarkably obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a main configuration of an image forming apparatus according to an embodiment of the invention.

FIG. 2 is a perspective view illustrating a configuration of an aperture electrode body used in the image forming apparatus.

FIG. 3A is an enlarged front view of the vicinity of the aperture according to the first embodiment, FIG. 3B is a cross-sectional view taken along line AA of FIG.
(C) is a rear view.

FIG. 4A is an enlarged surface view near the aperture according to the second embodiment, FIG. 4B is a cross-sectional view taken along line AA of FIG.
(C) is a rear view.

FIG. 5A is an enlarged surface view of the vicinity of an aperture according to the third embodiment, FIG. 5B is a cross-sectional view taken along line AA of FIG.
(C) is a rear view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aperture electrode body (charger control means) 2 Insulating sheet 4 Control electrode 6 Aperture 7 Convex part 14 Toner carrying roller (charger carrying body) 16 Toner (charger) 22 Back electrode roller (back electrode)

Claims (4)

[Claims] 1. A charged body control means having an opening and a control electrode provided corresponding to the opening, a charged body support for carrying and transporting a charged body to the charged body control means, and a charged body support The body comprises a back electrode provided on the opposite side with respect to the charged body control means, and controls passage of electricity to the control electrode so that the charged body carried by the charged body carrier passes through the opening. In the image forming apparatus for controlling and forming an image on a support supported on the back electrode, the charged body control means includes a charged body to be carried and conveyed by the charged body carrier and to enter the opening An image forming apparatus provided with means for mechanically acting on the charged body to change the restraining force received by the charged body from the charged body carrier and guiding the charged body in the opening direction. 2. The charged body control means is provided with a convex portion divided corresponding to the opening on an upstream side in a direction of transport of the charged body by the charged body carrier.
An image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 2, wherein the convex portion is gently raised in a direction in which the charged body is transported by the charged body carrier. 4. A control electrode of the charged body control means is provided on an insulating sheet member, and a surface of the insulating sheet member opposite to a surface on which the control electrode is provided is the charged body carrier. 4. The image forming apparatus according to claim 2, wherein the convex portion is provided on a side in contact with the charge carrier. 5.